watchface_replace_dial_bg_file

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description must fully disclose behavioral traits. It accurately describes the mutation (replaces cached bitmap) and validation steps, but does not mention authentication requirements, potential side effects (e.g., whether the device restarts), or the response format. The description partially covers transparency but leaves gaps.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single, dense paragraph that front-loads the core purpose and constraints. It efficiently conveys technical details without unnecessary words, but could be structured into bullet points for clarity. It earns its place with every sentence, achieving conciseness.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool has 6 parameters, an optional target object, and no output schema, the description covers the main validation rules and multipart behavior but omits explanation for clockId and useCurrentDisplayClock. It also lacks return value information. The description is fairly complete for the core behavior but misses some contextual details.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 67%, and the description adds value by explaining file validation and multipart framing beyond the schema. However, it does not clarify the meaning of clockId or useCurrentDisplayClock, which remain undocumented. The description compensates somewhat but not fully for the missing parameter details.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool replaces the cached dial bitmap via POST, and explicitly distinguishes itself from siblings by noting it does not modify DeviceImageUrl and does not accept tar.gz. It also specifies the targeted resource (clock dial background) and the HTTP method, leaving no ambiguity about its function.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides file validation details (JPEG/WebP, ≤500 KiB, recommended 800x1280) but does not explicitly state when to use this tool vs alternatives like watchface_upload_file or watchface_patch_local. It implies context for replacing a dial background without changing the rest of the watchface, but lacks direct when-to-use or when-not-to-use guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.